Assemble different types, refactor GeoJSON serialization, general improvements (#43)

* #19, #20, #21, refactor

* convert GeoJSONObjectType to enum, rename

* rm overridden bboxes

* Implement vector operations #23

* statically type 'round' helper func, fix unit test

* gen coverage

* fix typo

* geojson unit tests, type fixes

* fix deserialization with GeoJSONObjectType, implement hashCode

* initial unit tests for new constructors

* integration tests

* fix path

* test bbox on other geojson types

* update enum tests

* required params for new constructors, unit tests

* license notices

Author: lukas-h

.gitignore

@@ -9,3 +9,5 @@ build/
 
 # Directory created by dartdoc
 doc/api/
+
+coverage/